I'm facing a strange problem in python. I have a maze, x's stand for walls, g is a goal, s is the starting point and the numbers are portals which bring you from one number to the other (e.g. if you go on one of the 2's it will transport you to the other 2).
xxxxxxxxxxxxxxxxxxxx
x2 x
x xxx x
x 1 x xxxxx x
x s x x
x x x xxxxxxx
x xx xxxxx x
x x g x
x 1 x 2 x
xxxxxxxxxxxxxxxxxxxx
I'm trying to find all portals and put them into an array. So far this works, the program finds all four portals.
import tkinter as tk
from tkinter import filedialog
root = tk.Tk()
root.withdraw()
file = filedialog.askopenfilename()
def readMazeToArray(path):
with open(path) as f:
return [list(line.strip()) for line in f]
maze = readMazeToArray(file)
def findPortals(maze):
portals = []
for i in range(0, len(maze)):
for j in range(0, len(maze[i])):
if (maze[i][j] != 'g' and maze[i][j] != 's'
and maze[i][j] != 'x' and maze[i][j] != ' '):
portals.append([i, j])
return portals
And from then on things are getting a bit strange. Here's the code that doesn't seem to work right:
def portalHeuristic(maze, x1, x2, y1, y2):
portals = findPortals(maze)
for portal in portals:
for i in range(0, len(maze)):
for j in range(0, len(maze[i])):
if maze[i][j] == maze[portal[0]][portal[1]]
and (portal[0] != i or portal[1] != j):
return abs(x1 - portal[0]) + abs(y1 - portal[1])
+ abs(x2 - i) + abs(y2 - j))
print(maze[i][j] == maze[portal[0]][portal[1]])
print("x1 = ", x1, ", y1 = ", y1, ", portal0 = ",
portal[0], ", portal1 = ", portal[1], ", x2 = ",
x2, ", y2 = ", y2, ", i = ", i, ", j = ", j)
portalHeuristic(maze, 4, 4, 7, 14)
What portalHeuristic basically does is it now iterates through one portal after another looking for the same symbol (maze[i][j] == maze[portal[0]][portal[1]]) of the current portal but ensures that it didn't find the current portal itself by comparing the coordinates of the current portal and the portal it has found with the same symbol/ number (portal[0] != i or portal[1] != j). Eventually it computes the distance between starting point and current portal and its twin portal and the goal.
But it seems like maze[i][j] == maze[portal[0]][portal[1]] doesn't seem to work since my program always tells me the other portal was found at i=9, j=19, no matter which portal. Strangely enough if I test for the equality of the strings on its own python realizes that it is always false. What am I doing wrong? I've now spent more than 3 hours looking for the error, but I can't seem to find it. Maybe it's a really stupid one?
Also, please bear with my terrible code. I just started with python.
its hard to write out for loops once you're familliar with list comprehensions
but perhaps you can work backwards from my example list comps with http://treyhunner.com/2015/12/python-list-comprehensions-now-in-color/
I added line breaks and leading whitespace inside the listcomps in an atempt to help readability
you should also see that enumerate is very helpful in these types of indexing loops with test on elements
maze = ['xxxxxxxxxxxxxxxxxxxx',
'x2 x',
'x xxx x',
'x 1 x xxxxx x',
'x s x x',
'x x x xxxxxxx',
'x xx xxxxx x',
'x x g x',
'x 1 x 2 x',
'xxxxxxxxxxxxxxxxxxxx']
prtls = [[c, (j, k)]
for k, ln in enumerate(maze)
for j, c in enumerate(ln) if c.isdigit()]
prtls
Out[206]: [['2', (1, 1)], ['1', (4, 3)], ['1', (4, 8)], ['2', (10, 8)]]
grpd_prtls = [[n, [p[1]
for p in prtls if p[0] == n]]
for n in sorted(set(p[0] for p in prtls))]
grpd_prtls
Out[207]: [['1', [(4, 3), (4, 8)]], ['2', [(1, 1), (10, 8)]]]
the grpd_prtls is sorted by portal number sorted(set(p[0] for p in prtls))
to calc 'Manhatten Distance' from my grpd_prtls, assmuming just 2 portals per number
[[p[0], sum(abs(a-b)
for a, b in zip(*p[1]))]
for p in grpd_prtls]
Out[214]: [['1', 5], ['2', 16]]